Method and device for allocating radio resources in wireless portable network system

ABSTRACT

Information for different subscribers of a service with the same modulation and channel encoding method is transmitted by allocating radio resources in a wireless portable Internet system. Also, identifier information on the subscriber of a concurrently allocated radio resource is transmitted through common control information. Therefore, information for a plurality of subscribers coexists in a single radio resource block, and it can be easily transmitted. Since a subscriber station which has received downlink information can know to which radio resource block the information for the corresponding station is allocated through the subscriber identifier information transmitted as common control information, the subscriber station can access desired information by accessing a specific radio resource block to which information for the subscriber is allocated in the received frame.

CROSS REFERENCE TO RELATED APPLICATION

This application is the National Phase application of InternationalApplication No. PCT/KR2004/001781, filed Jul. 16, 2004, which designatesthe United States and was published in English. This application, in itsentirety, is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a method and device for allocatingradio resources in a wireless portable network system. Morespecifically, the present invention relates to a radio resourceallocating method and device for accessing a radio resource to whichpacket data for a corresponding subscriber station are allocated, andretrieving information by allocating a radio resource and transmittingsubscriber information when allocating the resource of a downlink in awireless portable network system.

BACKGROUND ART

A wireless portable Internet is a next generation communication methodfor further supporting nobility for short range data communicationmethods which use fixed access points, such as the conventional wirelessLAN.

Various standards for the wireless portable Internet have been proposed,and the international standard of the portable Internet has progressedby focusing on the IEEE 802.16e.

FIG. 1 shows a brief diagram of the wireless portable Internet.

A wireless portable Internet system comprises an SS (subscriberterminal) 10, base stations 20 and 21 for performing wirelesscommunication with the SS 10, routers 30 and 31 connected to the basestations through a gateway, and the Internet.

The wireless LAN method such as the conventional IEEE 802.11 provides adata communication method for allowing short-range wirelesscommunication with reference to a fixed access point, and it does notprovide nobility of the SS but rather it supports the short-range datacommunication in a wireless manner instead of on the cable basis.

The wireless portable Internet system driven by the IEEE 802.16 groupguarantees mobility and provides a seamless data communication servicewhen the SS 10 shown in FIG. 1 is moved to a cell managed by the basestation 21 from another cell managed by the base station 20.

The IEEE 802.16 basically supports the MAN (metropolitan area network),and represents an information communication network covering anintermediate area of between the LAN and the WAN.

Therefore, the wireless portable Internet system supports a handover ofthe SS 10 in a like manner of the mobile communication service, andassigns dynamic 1P addresses according to movement of the SS.

In this instance, the SS communicates with the base stations 20 and 21through the OFDMA (orthogonal frequency division multiple access)method, which is a multiplexing method having combined the FDM(frequency division multiplexing) method which uses a plurality ofsubcarriers of orthogonal frequencies as a plurality of subchannels, andthe TDM (time division multiplex) method. The OFDMA method isessentially resistant to the fading phenomenon generated on themulti-paths, and has high data rates.

Also, the IEEE 802.16 has adopted the AMC (adaptive modulation andcoding) method for adaptively selecting a modulation and coding methodaccording to a request and an acceptance between the SS 10 and the basestations 20 and 21.

FIG. 2 shows a hierarchical structure of the wireless portable Internetsystem.

The hierarchical structure of the wireless portable Internet system ofthe IEEE 802.16e is generally classified as a physical layer L10, and anMAC (media access control) layer L21, L22, and L23.

The physical layer L10 performs wireless communication functionsexecuted on the conventional physical layers, such as modulation,demodulation, and encoding.

The wireless portable Internet system does not have layers classifiedaccording to their functions, but allows a single MAC layer to performvarious functions, differing from the wired Internet system.

Regarding sublayers according to the functions, the MAC layer comprisesa privacy sublayer L21, an MAC common part sublayer L22, and a servicespecific convergence sublayer L23.

The service specific convergence sublayer L23 performs a payload headersuppression function and a QoS mapping function in the case ofconsecutive data communication.

The MAC common part sublayer L22, which is the core part of the MAClayer, performs a system access function, a bandwidth allocationfunction, a connection establishing and maintenance function, and a QoSmanagement function.

The privacy sublayer L21 performs a device authentication function, asecurity key exchange function, and an encryption function. Deviceauthentication is performed by the privacy sublayer L21, and userauthentication is performed by an upper layer (not illustrated) of theMAC.

FIG. 3 shows a brief diagram of a connection configuration between a BS(base station) and an SS in the wireless portable Internet system.

The MAC layer of the SS and the MAC layer of the BS have a connection C1therebetween.

The phrase connection C1 in the present invention represents not aphysically connected relation but rather a logically connected relation,and it is defined to be a mapping relation between MAC peers of the SSand the BS in order to transmit traffic of a single service flow.

Therefore, parameters or messages defined with respect to the connectionC1 represent the functions between the MAC peers, and in reality, theparameters or the messages are processed, are converted into frames, andare transmitted through the physical layers, and the frames are parsedand the functions which correspond to the parameters or the messages areexecuted on the MAC layer.

The MAC messages include various messages for performing a request REQ,a response RSP, and an acknowledgment ACK for various operations.

FIG. 4 shows a frame diagram for illustrating resource allocation in aconventional wireless communication system.

The conventional cellular system for packet transmission allocates theradio resources in a shared channel format in order to effectively usethe radio resources other than using a dedicated channel for randomsubscribers when using burst characteristics of packet data andallocating the radio resources for data transmission. Therefore, evenone radio resource can transmit packet data for a plurality ofsubscribers. Also, since a subscriber station receives a uniqueidentifier for distinguishing subscribers from a mobile communicationnetwork and concurrently receives a plurality of services with differentQoS (quality of service), it receives a CD (connection identifier) anddistinguishes services which one subscriber can concurrently receive.

As to the resource allocation diagram in the OFDMA system shown in FIG.4, the horizontal axis indicates time-divided symbols and the verticalaxis represents subchannels including a plurality of subcarriers. Radioresources WM1 to WM9 in the system are allocated in the square formats.The prior art generally suggests two methods for allocating the radioresources WM1 to WM9 to the subscriber.

FIG. 5 shows a conventional radio resource allocation method.

The first prior art allows the station to access the radio resource ofthe downlink allocated to the station as the radio resources WM1 to WM9and the subscriber station information have 1:1 mapped relations. Theprior art advantageously provides the subscriber station easy access tothe radio resource and less power consumption, but cannot allocateefficient radio resources, as an empty resource space which fails totransmit data in the radio resource space is generated since it isdifficult to accurately control the allocated two-dimensional area andthe quantity of the packet data because of the characteristics ofallocation of the radio resources allocated in the two-dimensionalsquare structure based on the data transmit symbol units on the temporalaxis and the subcarriers on the radio resource axis.

That is, as shown in FIG. 5, it is not guaranteed that the radioresource WMn allocated to a specific subscriber station is filled withthe packet data P1 to P7, and the resource corresponding to the space Sis problematically lost.

FIG. 6 shows another conventional radio resource allocation method inwhich information for a plurality of subscribers and a plurality ofservices with different connection identifiers concurrently provided toa subscriber station are allocated altogether.

This conventional method minimizes the area through which the data arenot transmitted in the allocated two-dimensional radio resource space tothus maximize the efficiency of the allocated radio resource, but whenthe subscriber station SS receives a downlink, the subscriber stationfails to detect the radio resource to which the packet data of thesubscriber station are allocated, and hence, the subscriber station isto access all the radio resource blocks WM1 to WM10 transmitted to thedownlink and retrieve information on the respective connections.

Therefore, the conventional method increases power consumption and isnot appropriate for usage for the wireless portable Internet subscriberstations. That is, the above-described prior art are ineffective in theusage of radio resources and limit mobility of the subscriber stationsbecause of large power consumption.

DISCLOSURE OF INVENTION

Technical Problem

It is an advantage of the present invention to provide a method anddevice for allowing low power consumption of mobile subscriber stationsand increasing efficacy of battery usage by allocating a radio resourceof a downlink, and concurrently transmitting subscriber information,accessing the radio resource to which packet data for a correspondingsubscriber station is allocated, and retrieving information in awireless portable network system.

In detail, the services with the same modulation and channel encodingmethods combine the services having information on different subscribersand having different connections for one subscriber into a single group,allocate radio resources thereto, and transmit them. Also, informationon the subscriber identifier on the allocated radio resource istransmitted through common control information. Therefore, informationon a plurality of subscribers can be loaded on a single radio resourceblock, and can then be transmitted, and since the subscriber stationhaving received downlink information can detect to which radio resourceblock the information for the corresponding station is allocated throughthe subscriber identifier information transmitted through the commoncontrol information, the present invention provides a method and devicefor acquiring information by accessing the specific radio resource blockto which information for the subscriber is allocated in the receivedframe.

Technical Solution

In one aspect of the present invention, a method for allocating downlinkradio resources in a wireless portable network system, comprises: (a)determining a modulation and channel encoding level of the respectiveradio resources according to radio channel characteristics; (b)generating subscriber station information on the radio resources; (c)mapping the subscriber station information to common controlinformation; and (d) transmitting the allocated radio resource and thecommon control information to the downlink.

The step (c) comprises: mapping modulation and channel encoding levelinformation of the respective radio resources to the common controlinformation; and mapping time-based and frequency-based offsetinformation of the respective radio resources to the common controlinformation.

The subscriber station information comprises identifier information onthe subscriber stations which access the respective radio resources, andinformation on numbers of the subscriber stations.

In another aspect of the present invention, a method for accessingdownlink radio resources in a wireless network system, comprises: (a)allowing a subscriber station to receive a radio resource and a commoncontrol information block which stores subscriber station information onthe radio resource; (b) retrieving a corresponding subscriber stationidentifier within the common control information block; (c) reading amodulation and channel encoding level of the corresponding radioresource from common control information corresponding to the retrievedsubscriber station identifier, and determining a demodulation andchannel decoding level; (d) checking the corresponding radio resourcefrom the common control information corresponding to the retrievedsubscriber station identifier; and (e) accessing the checked radioresource and receiving data information corresponding to the subscriberstation by the determined demodulation and channel decoding method.

The step (d) comprises reading symbol-based offset information andsubcarrier-based offset information of the corresponding radio resourcefrom the common control information.

In still another aspect of the present invention, a base station devicefor allocating radio resources in a wireless portable network system,comprises: a base station controller including a radio resourceallocator for allocating downlink data of subscriber stations which usethe same modulation and channel encoding level to a single radioresource, and mapping information on the subscriber stations and themodulation and channel encoding level information to the common controlinformation block; a digital signal transmitter for modulating andchannel-encoding the radio resources allocated by the radio resourceallocator with a specified identical modulation and channel encodinglevel; and an analog signal transmitter for converting the modulated andchannel-encoded digital signals into analog signals, and transmittingthe analog signals to the subscriber station.

The radio resource allocator comprises: a modulation level establisherfor establishing a modulation level of the data to be allocated to aradio resource according to a characteristic of a radio channel, andmapping the level information to the common control information block; achannel encoding level establisher for establishing a channel encodinglevel of the data to be allocated to the radio resource according to acharacteristic of a radio channel, and mapping the level information tothe common control information block; a subscriber station establisherfor mapping a subscriber identifier assigned to the radio resource to acommon control block; and an offset establisher for establishing aposition and a size of the radio resource on a frame by symbol offsetsand subcarrier offsets, and mapping the offset information to the commoncontrol information block.

In still yet another aspect of the present invention, a subscriberstation device for accessing radio resources in a wireless portablenetwork system, comprises: an analog signal receiver for receivinganalog radio signals and converting them into digital signals; a stationcontroller including a common control information reader for readingtransmitted common control information, and retrieving information onthe radio resource to be accessed by the subscriber station device; anda digital signal receiver for performing demodulation and channeldecoding according to the modulation and channel encoding level of theradio resource retrieved by the common control information reader, andreceiving data information.

The common control information reader comprises: a subscriber stationidentifier retriever for retrieving radio resource information includingsubscriber station identifiers from the common control informationblock; a modulation and encoding level reader for modulation andencoding level information of the retrieved radio resource; and anoffset information reader for reading symbol-based offset informationand subcarrier-based offset information of the retrieved radio resource.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate an embodiment of the invention,and, together with the description, serve to explain the principles ofthe invention:

FIG. 1 shows a brief diagram of the wireless portable Internet;

FIG. 2 shows a hierarchical structure of the wireless portable Internetsystem;

FIG. 3 shows a brief diagram of a connection configuration between a BSand an SS in the wireless portable Internet system;

FIG. 4 shows a frame diagram for illustrating resource allocation in aconventional wireless communication system;

FIG. 5 shows a conventional radio resource allocation method;

FIG. 6 shows another conventional radio resource allocation method;

FIG. 7 shows allocation of radio resources according to a preferredembodiment of the present invention;

FIG. 8 shows a configuration diagram of a common control informationblock according to a preferred embodiment of the present invention;

FIG. 9 shows a configuration diagram of a base station in a radioresource allocator according to a preferred embodiment of the presentinvention;

FIG. 10 shows a configuration diagram of a radio resource allocationunit of a base station according to a preferred embodiment of thepresent invention;

FIG. 11 shows a configuration diagram of a station of a radio resourceallocator according to a preferred embodiment of the present invention;

FIG. 12 shows a block diagram of a common control information readeraccording to a preferred embodiment of the present invention;

FIG. 13 shows a flowchart for a radio resource allocating methodaccording to a preferred embodiment of the present invention; and

FIG. 14 shows a flowchart of a method for a subscriber station to accessa downlink radio resource according to a preferred embodiment of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following detailed description, only the preferred embodiment ofthe invention has been shown and described, simply by way ofillustration of the best mode contemplated by the inventor(s) ofcarrying out the invention. As will be realized, the invention iscapable of modification in various obvious respects, all withoutdeparting from the invention. Accordingly, the drawings and descriptionare to be regarded as illustrative in nature, and not restrictive. Toclarify the present invention, parts which are not described in thespecification are omitted, and parts for which similar descriptions areprovided have the same reference numerals.

A radio resource allocating method and device according to a preferredembodiment of the present invention will be described in detail withreference to drawings.

FIG. 7 shows allocation of radio resources according to a preferredembodiment of the present invention.

The radio resource according to the preferred embodiment of the presentinvention comprises two-dimensional radio resource blocks WM1 to WM8 inthe square format, and a common control information block (C1) includinginformation on the allocated radio resource.

As described, the radio resource blocks WM1 to WM8 and the commoncontrol information block (C1) are formed in the two-dimensionalstructure of subcarriers and time-divided symbols. The radio resourceblocks WM1 to WM8 have the sane modulation and channel encoding level,and comprise service information on a plurality of subscriber stations.Therefore, the respective radio resource blocks WM1 to WM8 respectivelyinclude subscriber identifiers. For example, the radio resource blockWM5 includes a plurality of subscriber identifiers SSD#1, SSD#3, SSD#7,and SSD#8.

The common control information block (C1) includes information on therespective radio resources WM1 to WM8 included in the frame. Forexample, common information control information M1 to M8 displayincluded states of subscriber identification information allocated tothe radio resources WM1 to WM8, and the common information controlinformation M5 including subscriber identification information has radioresource allocation information on the radio resource WM5.

Therefore, the subscriber stations can receive the common controlinformation block (C1), retrieve desired radio resource information, andaccess corresponding radio resources.

In its actual realization, the station in the case of FIG. 7 may bufferthe radio resource WM1 which is received at the same time as that of thecommon control information block, and may buffer the radio resourcesWM2, WM3, and WM4 depending on performance of the station since aprocessing time is needed until the station receives information of thecommon control information block (a) and reads correspondinginformation. This buffering process may substantially increase thebuffer size required by the station, for example, the station which hasan allocated resource block of the station in the radio resource WM1 mayhave a loss on the processing time since the station starts an access tothe allocated resource block of the station after finishing reading thecommon control information block. Further, the size of the commoncontrol information block including subscriber identificationinformation of the radio resources can be increased, which may bedisadvantageous for effective usage of radio resources. Therefore, areceiver of the station can consider a processing time which is requireduntil reading the common control information block, and it may notinclude subscriber identification information on part of the former oneof the downlink radio resources into the common control informationblock but it may include the subscriber identification information intothe subsequent radio resources (the radio resources WM5 to WM8 in thecase of FIG. 7), and transmit them.

In this instance, the stations receive the common control informationblocks, read them, check included states of subscriber identificationinformation, access the radio resource blocks which include nosubscriber identification information, retrieve whether downlink datatransmitted to the stations are provided thereto, read subscriberidentification information of the radio resource blocks which includethe subscriber identification information of the corresponding radioresource in the common control information blocks, and thus retrieve theradio resource blocks allocated to the stations.

Also, when the station previously has knowledge on included states ofallocation information on the radio resource included in the commoncontrol information block in the above-noted example (e.g., if thestation knows a rule that the subscriber identification information onthe radio resources WM1 to WM4 is not included in the common controlinformation block), the station directly accesses the radio resourcesWM1 to WM4 to find radio resource blocks allocated to the station(without reading the subscriber identification information from thecommon control information block) in the case of the radio resources WM1to WM4, and the station accesses the radio resource blocks allocated tothe station according to the subscriber identification informationallocated to the respective resources WM5 to WM8 obtained through thecommon information control block in the case of the radio resources WM5to WM8.

FIG. 8 shows a configuration diagram of common control informationaccording to a preferred embodiment of the present invention.

The common control information of the radio resource WM5 comprisesmodulation and channel encoding level information F1 of a correspondingradio resource, symbols and subchannels offset information F2, numbersof subscriber identifier information F3, and subscriber identifierinformation F4.

The modulation and channel encoding level information F1 of the radioresource includes common modulation and channel encoding information ofthe corresponding radio resource WM5. As described above, the radioresources are allocated based on the identical modulation and channelencoding information.

The symbols and subchannels offset information F2 includes offsetinformation on the vertical axis and the horizontal axis of thecorresponding radio resource WM5, and hence, it provides positioninformation on the radio resource WM5 corresponding to the offset of thesymbol and the subchannel.

The numbers of subscriber identifier information F3 indicates numbers ofsubscriber stations which use the radio resource WM5.

The subscriber identifier information F4 includes identifiers ofsubscriber stations which use the radio resource WM5.

Therefore, the subscriber stations of the downlink receive the commoncontrol information block (C1) through a broadcast channel, and retrieveradio resources to which subscriber identifiers of the subscriberstations are provided. When the radio resource to which the subscriberidentifier of the subscriber station is provided is found, thesubscriber station reads the position of the radio resource and themodulation and channel encoding information, and accesses the radioresource allocated to the subscriber station. As shown in FIG. 7, sincethe radio resource comprises subscriber identifiers of information on aplurality of services, the subscriber station can receive the serviceinformation which includes the subscriber identifier of the subscriberstation from among the radio resources accessed by the subscriberstation.

FIG. 9 shows a configuration diagram of a base station 100 in a radioresource allocator according to a preferred embodiment of the presentinvention.

The base station 100 comprises a base station controller 110, a digitalsignal transmitter and receiver 130, and an analog signal transmitterand receiver 140. The base station controller 110 comprises a radioresource allocator 120 for allocating radio resources, and the digitalsignal transmitter and receiver 130 comprises a transmitter 131 forselectively performing transmit/receive functions, and a receiver 132.

The radio resource allocator 120 allocates subscribers who use theidentical modulation and channel encoding and services which havedifferent connection identifiers within the identical subscribers to asingle block in the radio resources so as to be fit to the QoS of thepacket data to be transmitted to the downlink. Also, the radio resourceallocator 120 allocates per-subscriber packet data to each radioresource block in the modulation and channel encoding level allowed bythe system in a like manner. The allocated subscriber information andthe modulation and channel encoding information of the radio resourceare mapped to the common control information block.

The transmitter 131 modulates and encodes modulation and channelencoding level information of the radio resource block within a frame,symbols and subchannels offset information, numbers of the subscriberstations allocated to the radio resource block, and the correspondingstation identifier information in the common control information blockaccording to the modulation and channel encoding level so that thestation may appropriately demodulate and channel-decode the data withinthe received radio resource.

The modulated and encoded radio resource block is transmitted to thesubscriber station by air by using the analog signal transmitter andreceiver 140.

FIG. 10 shows a configuration diagram of a radio resource allocationunit of a base station according to a preferred embodiment of thepresent invention.

The radio resource allocator 120 comprises a modulation levelestablisher 122, a channel encoding establisher 123, a subscriberstation establisher 124, a symbol and subchannel offset establisher 125,and a controller 121.

The modulation level establisher 122 and the channel encodingestablisher 123 select the identical modulation level and the channelencoding level and allocate them to the same radio resource according tothe QoS policy. For example, they select the QPSK, 16-QAM, and 32-QAMfor the modulation level according to characteristics (e.g., the SNR(signal to noise ratio)) of the physical channel of the downlink, andselect the BTC, CTC, or RM encoding method for the channel encodinglevel. The modulation level establisher 122 and the channel encodingestablisher 123 map the established modulation and channel encodinglevel information to the common control information block.

The subscriber station establisher 124 provides data included in theallocated radio resource, and a subscriber identifier to be used for thecommon control information block so that the subscriber station raydistinguish a radio resource to be accessed by the subscriber stationthrough the common control information block and distinguish the data ofthe subscriber station from among the radio resource in the case of thedownlink.

The symbol and subchannel offset establisher 125 specifies thetwo-dimensional position and size of the allocated radio resource on theframe by specifying a symbol-based offset on the temporal axis and asubchannel-based or, subcarrier-based) offset on the frequency axis. Theoffset unit on the frequency axis is given with the subchannel in thepreferred embodiment, and the same can be given with the subcarrier. Theoffset information is mapped to the common control information block tothus provide position information of the radio resource allocated to thesubscriber station.

The controller 121 controls the modulation level establisher 122, thechannel encoding establisher 123, and the subscriber station establisher124 to thereby control radio allocation.

FIG. 11 shows a configuration diagram of a station 200 of a radioresource allocator according to a preferred embodiment of the presentinvention.

The station 200 comprises a station controller 210, a digital signaltransmitter and receiver 230, and an analog signal transmitter andreceiver 240. The station controller 210 comprises a common controlinformation reader 220. The digital signal transmitter and receiver 230comprises a transmitter 231 for transmitting and receiving digitalsignals, and a receiver 232.

The common control information reader 220 reads the common controlinformation transmitted to all the stations through the broadcastchannel, and retrieves a desired radio resource. The station controller230 controls the digital signal transmitter and receiver 230 accordingto reading results of the common control information reader 220, anddemodulates and decodes the data of the radio resource through anappropriate demodulation and channel decoding method.

FIG. 12 shows a block diagram of a common control information readeraccording to a preferred embodiment of the present invention.

The common control information reader 220 comprises a subscriber stationidentifier retriever 221, a modulation and encoding level reader 222, anoffset information reader 223, and a data information retriever 224.

On receiving a common control information block, the station 200 usesthe subscriber station identifier retriever 221 of the common controlinformation reader 220 to retrieve whether the radio resource which hasthe subscriber station identifier of the station 200 is provided in thecommon control information block.

When the radio resource including the identifier of the station 200 isfound, the modulation and encoding level reader 222 reads modulation andencoding level information of the corresponding radio resource from thecommon control information block. The modulation and encoding levelinformation is transmitted to the receiver of the digital transmitterand receiver, and is used for demodulating and decoding the radioresource.

The offset information reader 223 reads a subchannel-based offset (or, asubcarrier-based offset) and a symbol-based offset, and detects theposition of the allocated radio resource.

When the position of the radio resource is found, the data informationretriever 224 retrieves data information which has the subscriberidentifier of the data information retriever 224 from among the datainformation for a plurality of subscribers from among the radioresources. The station controller 210 controls the station to access theradio resource and the data information allocated to the stationcontroller 210.

According to the above-described configuration, the station analyzesinformation on the common control block having the characteristic ofbroadcast information, checks whether a radio resource allocated to thestation is provided, acquires modulation and encoding level informationof the corresponding radio resource, and demodulates and decodes thecorresponding radio resource with an adequate level. Accordingly, thestation does not need to check all the transmitted radio resources, andthe radio resources are appropriately managed to fit to the QoS policywithout waste of power consumption.

FIG. 13 shows a flowchart for a radio resource allocating methodaccording to a preferred embodiment of the present invention.

The base station catches a radio channel characteristic of the downlinkthrough an MAC message (e.g., a channel descriptor message) fordescribing the characteristic of the physical layer in step S10.

The base station adaptively determines a modulation and channel encodinglevel according to the characteristic of the physical layer caughtthrough the MAC message in step S11. For example, the modulation andchannel encoding level is determined according to the SNR caught in thephysical layer.

When the modulation and channel encoding level is determined, a radioresource corresponding to the modulation and channel encoding level isallocated in step S12. The radio resource determines the symbol-basedoffset and the subchannel-based (or, subcarrier-based) offset, anddetermines the position and the size on the frame.

When the radio resource is allocated, subscriber information on theallocated radio resource is generated, and it is mapped to the commoncontrol information block in step S13. When subscriber information onthe radio resource allocation and the radio resource is mapped to thecommon control information block, packet data are generated into framesand the frames are transmitted to the downlink in step S14.

FIG. 14 shows a flowchart of a method for a subscriber station to accessa downlink radio resource according to a preferred embodiment of thepresent invention.

When receiving the common control information block transmitted throughthe broadcast channel of the downlink, the subscriber station retrieveswhether the subscriber identifier of the subscriber station is providedin the common control block in step S20. The common control blockincludes subscriber information on the respective radio resourcesallocated according to the identical modulation and channel encodinglevel.

When the common control block including the subscriber identifier of thesubscriber station is found, the subscriber station reads the modulationand channel encoding level of the radio resource corresponding to thecommon control information block, and selects a demodulation and channeldecoding level of the subscriber station in order to receive themodulation and channel encoding level in step S21.

When the subscriber identifier is retrieved, the subscriber stationchecks the position and the size of the radio resource to whichinformation for the corresponding station is mapped in step S22.

When the radio resource allocated to the subscriber station isallocated, the subscriber station accesses the radio resource accordingto the selected demodulation and channel decoding method, retrieves thedata allocated to the corresponding station, and receives the same instep S23.

As known from the above-described embodiment, loss of the radioresources is prevented since the radio resources are allocated based onthe identical modulation and channel encoding level. The subscriberstation initially receives the common control information, acquiresinformation on the radio resource, acquires information on the radioresource to be accessed by the subscriber station, and accesses theradio resource. Therefore, power consumption is saved since there is noneed to access all the radio resources, and the power consumptionsupports high mobility in the wireless Internet system which generallyuses batteries.

While this invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not limited to thedisclosed embodiments, but, on the contrary, is intended to covervarious modifications and equivalent arrangements included within thespirit and scope of the appended claims.

According to the above-mentioned configuration, when allocating theradio resource of the downlink, subscriber information is transmitted tothe common control information block, the corresponding subscriberstation accesses the radio resource to which the packet data of thesubscriber station are allocated, and retrieves desired information, andaccordingly, low power consumption of the mobile subscriber station isallowed to thus maximize usage efficiency of batteries.

1. A method for a base station to transmit allocation information ofdownlink radio resource to a subscriber terminal in an OFDMA (OrthogonalFrequency Division Multiple Access) communication system, the methodcomprising: mapping, to a first region of a common control informationof the downlink radio resource, allocation information for at least onesubscriber terminal corresponding to a second region of the radioresource in a downlink frame composed of a predetermined number ofsymbols and a predetermined number of subchannels; and transmitting thecommon control information to the at least one subscriber terminal in atime duration of the downlink frame; wherein the allocation informationincludes: at least one identifier for the at least one subscriberterminal and a number of the at least one subscriber terminal; andsymbol offset information and subchannel offset information indicating atwo-dimensional position of the second region in the downlink frame. 2.The method of claim 1, further comprising mapping the symbol offsetinformation and the subchannel offset information of the second regionof the radio resource to the common control information of the downlinkradio resource.
 3. The method of claim 1, further comprising mapping themodulation and channel encoding information of the radio resource to thecommon control information of the downlink radio resource.
 4. The methodof claim 1, wherein when the downlink frame includes a plurality of thesecond regions, allocation information for at least one subscriberterminal corresponding to one of the second regions is mapped to thefirst region and allocation information for at least one subscriberterminal corresponding to the rest of the second regions is not mappedto the first region.
 5. A method for a subscriber terminal to access adownlink radio resource in an OFDMA (Orthogonal Frequency DivisionMultiple Access) communication system, the method comprising: receivinga common control information including a plurality of allocationinformation for a plurality of radio resource blocks in a downlink framecomposed of a predetermined number of symbols and a predetermined numberof subchannels, wherein each of the plurality of allocation informationincludes at least one identifier for at least one subscriber terminaland a number of the at least one subscriber terminal, and symbol offsetinformation and subchannel offset information indicating atwo-dimensional position of a radio resource block in the downlinkframe; searching allocation information corresponding to an identifierof the subscriber terminal among the plurality of allocationinformation; and accessing a radio resource block by using symbol offsetinformation and subchannel offset information corresponding to thesearched allocation information among the plurality of radio resourceblocks.
 6. The method of claim 5, wherein one of the plurality of radioresource blocks corresponding to the at least one allocation informationis allocated to the at least one subscriber terminal.
 7. The method ofclaim 6, wherein the at least one allocation information furthercomprises modulation and channel encoding information of thecorresponding radio block.
 8. The method of claim 5, wherein the commoncontrol information includes a plurality of allocation information for apart of the plurality of radio resource blocks and does not includeallocation information for the rest of the plurality of radio resourceblocks.
 9. The method of claim 8, further comprising accessing the restof the plurality of radio resource blocks and determining whether theidentifier corresponding to the subscriber terminal is included therein,wherein the searching allocation information including the identifiercorresponding to the subscriber terminal among the plurality ofallocation information for the part of the plurality of radio resourceblocks.
 10. An apparatus for transmitting allocation information ofdownlink radio resource to a subscriber terminal in an OFDMA (OrthogonalFrequency Division Multiple Access) communication system, the apparatuscomprising: means for mapping, to a first region of a common controlinformation block of the downlink radio resource, an allocationinformation for at least one subscriber terminal corresponding to asecond region of the radio resource in a downlink frame composed of apredetermined number of symbols and a predetermined number ofsubchannels; and means for transmitting the common control informationblock to the at least one subscriber terminal in a time duration of thedownlink frame; wherein the allocation information includes: at leastone identifier for the at least one subscriber terminal and the numberof the at least one subscriber terminal; and symbol offset informationand subchannel offset information indicating a two-dimensional positionof the second region in the downlink frame.
 11. The apparatus of claim10, further comprising means for mapping the symbol offset informationand the subchannel offset information of the second region to the firstregion in the downlink frame.
 12. The apparatus of claim 10, furthercomprising means for mapping modulation and channel encoding informationof the radio resource to the first region in the downlink frame.
 13. Themethod of claim 10, wherein when the downlink frame includes a pluralityof the second regions, allocation information for at least onesubscriber terminal corresponding to a part of the second regions ismapped to the first region and allocation information for at least onesubscriber terminal corresponding to the rest of the second regions isnot mapped to the first region.
 14. A method for a base station togenerate downlink frame in an OFDMA (Orthogonal Frequency DivisionMultiple Access) communication system, the method comprising: allocatinga radio resource block to the frame; allocating a common controlinformation block to the frame; determining whether to map, to thecommon control information block, allocation information for at leastone subscriber terminal corresponding to the radio resource block in adownlink frame composed of the predetermined number of symbols and thepredetermined number of subchannels; and mapping, to the common controlinformation block, at least one identifier for the at least onesubscriber terminal and a number of the at least one subscriberterminal, and symbol offset information and subchannel offsetinformation indicating a two-dimensional position of the radio resourceblock in the downlink frame when the allocation information for the atleast one subscriber terminal is mapped to the common controlinformation block.
 15. The method of claim 14, further comprisingmapping modulation and channel encoding information of the radioresource to the common control information block in the downlink frame.16. The method of claim 14, wherein when the downlink frame includes aplurality of radio resource blocks, allocation information for at leastone subscriber terminal corresponding to a part of the radio resourceblocks is mapped to the common control information block and allocationinformation for at least one subscriber terminal corresponding to therest of the radio resource blocks is not mapped to the common controlblocks.
 17. A method for a base station to generate downlink frame in anOFDMA (Orthogonal Frequency Division Multiple Access) communicationsystem, the method comprising: allocating a plurality of radio resourceblocks including a first radio resource block for at least one firstsubscriber terminal and a second radio resource block for at least onesecond subscriber terminal in a downlink frame composed of thepredetermined number of symbols and the predetermined number ofsubchannels; allocating a common control information block including aplurality of common control information to the frame, the plurality ofcommon information including a first common control information for thefirst radio resource block and a second common control information forthe second radio resource block; and mapping, to a common controlinformation of the common control information block, an allocationinformation for the at least one first subscriber terminal correspondingto the first radio resource block in the downlink frame; wherein theallocation information includes: at least one identifier for the atleast one first subscriber terminal and the number of the at least onefirst subscriber terminal; and symbol offset information and subchanneloffset information indicating a two-dimensional position of the firstradio resource block in the downlink frame.
 18. The method of claim 17,wherein an identifier for the at least one second subscriber terminaland the number of the at least one second subscriber terminal are notmapped to the second common control information.
 19. The method of claim17, further comprising mapping modulation and channel encodinginformation of the first radio resource to the first common controlinformation.